1. Field of the Invention
The present invention relates to a terminal double locking connector having a rear holder for locking a terminal, in which the rear holder reliably engages with a housing of the connector.
2. Prior Art
FIGS. 18 and 19 show a known terminal double locking connector disclosed in Japanese Patent Application Laid-open No. H. 8-88042.
As illustrated in FIG. 18, a double locking connector 41 has a synthetic resin, male-type connector housing 42, a rear holder 44 joined to the connector housing 42 via a pair of hinges 43, and receptacle-type terminals 45 inserted into the connector housing 42.
The rear holder 44 has terminal locking projections 46 in a fore end portion thereof for locking the terminals 45. The rear holder 44 has a final locking projection 47 (FIG. 19) in a rear end thereof for the holder 44 to be locked in the connector housing 42. The preliminary lock projection will not be further discussed herein. In FIG. 19, the connector housing 42 is upside-down as compared with that of FIG. 18. As illustrated in FIG. 19, the connector housing 42 has an opening 48 faced perpendicular to the terminal insertion direction. In a rear end portion of the opening 48, there is provided an engagement groove 49 mating with the final locking projection 47.
In a lock released state of the rear holder 44 shown in FIG. 18, the terminal 45 is forwardly inserted into the connector housing 42. The terminal 45 is preliminarily locked by a resilient lock lance 50 (FIG. 19) of the connector housing 42. Next, inserting the rear holder 44 diagonally forward into the connector housing 42 causes the terminal locking projection 46 to further lock the terminal 45 as illustrated in FIG. 19. On releasing of the terminal 45 for maintenance, the rear holder 44 is forcedly unlocked by using a bar tool (not shown) or the like so that the final locking projection 47 disengages from the groove 49 to release the rear holder 44.
In FIG. 19, denoted 51 is a female-type connector housing, 52 an opposing pin terminal, 54 a lock arm, 55 a lock projection of the lock arm 54, and 56 an engagement portion associated with the lock projection 55. The rear holder 44 is positioned as opposed to the lock arm 54.
However, the known double locking connector has the disadvantage that a repetition of engagement and disengagement of the rear holder 44 causes a wear or a permanent deformation (sagging) of the final locking projection 47, resulted in a reduced engagement force to bring about an unintentional release of the rear holder 44. In addition, a larger clearance between the rear holder 44 and the connector housing 42 tends to disengage the final locking projection 47 from the engagement groove 49, causing disadvantageously an unintentional release of the rear holder 44. Particularly, a larger drawing-out force exerted on an electric cable 53 tends to cause a lock release of the rear holder 44, which reduces the locking force of the terminal 45, resulting in an undesirable disengagement of the terminal 45 from the connector housing 42.
Meanwhile, FIGS. 20 and 21 show a known double locking connector disclosed in Japanese Patent Application Laid-open No. H. 8-298152.
As illustrated in FIG. 20, the double locking connector 100 consists of a male-type connector housing 103 formed with two-layered upper and lower terminal accommodating chambers 101, 102, a pair of rear holders (retainers) 107, 108 each inserted diagonally forward into one of upper and lower openings 104, 105 formed in a rear part of the connector housing 103, and receptacle-type terminals (not shown) received in the terminal accommodating chambers 101, 102. The pair of rear holders 107, 108 each have a shape different from each other.
The connector housing 103 has an upper wall formed with a resilient lock arm 109 for locking an opposing male-type connector (not shown). The lock arm 109 has a lock projection 110 in the middle thereof and has a push projection 111 at a rear end side thereof. The lock projection 110 engages with, for example, an opening formed in a hood wall of an opposing male-type connector housing (not shown). The upper rear holder 107 is inserted into the connector housing 103 with the holder crossing over the lock arm 109, and a narrow middle portion 112 of the rear holder 107 is positioned between the lock projection 110 and the push projection 111.
The upper opening 104 communicates with the terminal accommodating chambers 101 by way of entrance holes 113. In a rear end side of the opening 104, there is provided a guide inclined surface 114 for the rear holder 107. In each side portion of the opening 104 of the connector housing 103, there are provided a preliminary lock projection 115, a guide projection 116, and a final locking projection 117, which are associated with one of the rear holders 107, 108.
Each rear holder 107 or 108 has a base plate 118 or 119 and terminal locking projections 120 or 121. Each rear holder 107 or 108 has side walls 122, 123, and each side wall 122 or 123 has an engagement recess 124 receiving one of the projections 115 to 117 formed on the side portions of the connector housing 103. The upper rear holder 107 has a raised middle portion which is reduced in width. Meanwhile, the lower rear holder 108 transversely extends straight with a uniform width.
Inserting diagonally forward each rear holder 107 or 108 into the opening 104 or 105 of the connector housing 103 allows a preliminary lock of the rear holders 107, 108, as illustrated in FIG. 21. In this preliminary lock state, for example, there may be a clearance L2 between the side wall 122 of the rear holder 107 and a fore end of the opening 104 of the connector housing 103, and there may be also another clearance L3 between the middle portion 112 of the rear holder 107 and the lock projection 110. In the preliminary lock state, the connector housing 103 of the rear holder 107 receives the terminals (not shown) inserted therein.
A further advancement of the rear holder 107 abuts a fore end of the rear holder 107 against a fore edge of the opening 104, and the side final locking projections 117 finally lock the rear holder 107. Between the lock projection 110 and the middle portion 112 of the rear holder 107, there is a small clearance of L3-L2.
However, the known double locking connector 100 has the disadvantage that the rear holder 107 tends to be unintentionally drawn out diagonally upward along an inclined surface 114 (FIG. 20) of the connector housing 103. This unintentional drawn-out of the finally locked rear holder 107 occurs when an electric cable (not shown) connected to a terminal is forcibly pulled or when a terminal is forcibly pushed rearward on mating with an opposing connector. Particularly, since the connector housing 103 has the final locking projection 117 provided in each side thereof for engaging with the engagement portion 124 of the rear holder 107, the rear holder 107 tends to deflect at its middle part 112 by a forcible pulling force exerted on the electric cable with the terminal. This may cause a disengagement of the rear holder 107 against the lock force of the final locking projections 117. Furthermore, between the lock projection 110 and the middle part 112 of the rear holder 107, there is a small clearance of L3-L2 on a finally locked state of the rear holder 107. Thus, as illustrated in FIG. 22, the width L5 of an engagement portion 126 of an opposing male-type connector housing 125 must be smaller so as to be received within the distance L4 between the lock projection 110 and the push projection 111 of the lock arm 109. This causes a reduced rigidity of the engagement portion 126, resulted in an undesired unlock of the lock arm 109.